Is neuroscientific evidence now relevant to assessments of criminal responsibility?

Here’s an extract from Justice Kennedy’s comments on the recent decision in Graham v. Florida (2010) which raised an eyebrow (well, it raised my eyebrow anyway):

No recent data provide reason to reconsider the Court’s observations in Roper about the nature of juveniles. As petitioner’s amici point out, developments in psychology and brain science continue to show fundamental differences between juvenile and adult minds. For example, parts of the brain involved in behavior control continue to mature through late adolescence. (page 17)

As Professor Stephen J. Morse has argued, the court’s decision in Roper v. Simmons (2005) was not influenced by the substantial amount of neuroscientific evidence that was presented there; rather, the court based its decision purely on behavioural data.

But it seems that in the more recent Graham case the court was prepared to cite neuroscientific evidence as a consideration that diminishes the degree of juvenile offenders’ culpability.

The question that this raised in my mind is whether Graham marks a departure from Roper on the question of whether (and how) neuroscientific evidence is relevant to criminal responsibility assessments?